The present invention relates to the packaging of viscous food products. More particularly, the present invention relates to methods and apparatus for automated container filling for accurately, rapidly and continuously dispensing a desired weight of a viscous food product, such as cream cheese, sour cream, cottage cheese, and edible oils, into a plurality of successive product containers.
Conventionally, large containers for viscous food products such as cream cheese are fed along a production line into a station located beneath a spout from which cream cheese is discharged. The containers are positioned on a weighing scale which, through associated circuitry, terminates the flow of cream cheese from the spout when the scale indicates the desired amount of cream cheese had been introduced into the container. Similarly, edible oil products may be conventionally packaged by starting and stopping an oil pump mechanism in direct response to the container weight on a scale. While such conventional equipment and methods are acceptable for production purposes, they have certain disadvantages. For example, the actual weight of the cream cheese introduced into each respective container may vary and cannot readily be adjusted with a desired level of accuracy. The starting and stopping of pumping apparatus depends on a transient performance.
Substantial effort has been directed to the development of automatic weight and/or volume control systems for packaging operations. For example, automated hopper fill systems such as disclosed in U.S. Pat. Nos. 3,856,097, 3,837,415 and 4,129,189 utilize cumulating hoppers to meter product into containers. However, cream cheese is a viscous product which tends to stick irregularly to the sides of containers. Automated hopper weight control systems are accordingly not suitable for high speed, accurate in-line packaging systems for cream cheese or other viscous fluid food products, because the product will not dump with consistent repeatability from a hopper into a product container to provide packages of precise weight uniformity and accuracy.
Other development effort has been directed to volumetric measuring to achieve portion control, such as disclosed in U.S. Pat. No. 3,648,741. In the filling of bulk, institutional or industrial size packages, such as those containing in the weight range of from about 10 to about 50 pounds of product, high capacity pumping and filling rates are desirable for efficient operation. However, viscous food products such as cream cheese are subject to property variation, depending upon such factors as product temperature and the static head of product in the cooking kettles or storage tanks. Fluctuations in plant voltage and variations in product texture and consistency also provide difficulty for precise product process control and measurement, such that significant disadvantages in the use of a volumetric measuring cylinder for precisely filling large, bulk containers.
In addition, in order to provide a rapid filling rate with maximum throughput and operating efficiency, a product delivery pump desirably should run continuously to maintain reliable and predictable flow control. It is desirable to continuously transfer the viscous food product into containers rather than start and stop a food product pump or recycle the product back to a cooking kettle or other product source. Accordingly, it is an object of the present invention to provide improved methods and apparatus for rapidly and accurately packaging viscous food products. It is a further object to provide such methods and apparatus which are capable of adapting to changing conditions of product properties or operating conditions. These and other objects will become apparent from the following detailed description and the accompanying drawings.